Alright, it's more-or-less there, as there were a lot of bugs to fix as mentioned prior:

• Now you can push the cart on the rails, and nudge it very slow when not
• You can switch between 3 types of track: left, right, straight

While it's definitely not perfect, it is robust enough for a prototype. Switches and other useful bits are planned to be part of a commercial release, but not for a prototype. Now, time to make sure you can purchase and place the cart in-game (as currently the cart is being spawned in at the beginning), and be able to store ores and bring it home. Which is going to take a few days to code and test, especially knowing that mobs could attack the cart as well as destroy it (and loose a portion of the contents inside). See some of the progress below.